The proposed Ultrasonic Spatial Sensing Aid for the Blind is an electron travel aid designed to provide the blind traveler with spatial contextual information, a necessary prerequisite for mobility. The device operates on the echolocating principle, by broadcasting ultrasound which is reflected by environmental objects. The returning ultrasonic echoes will be electroacoustically transformed into audible sounds encoded with the complete set of sound localization cues responsible for spatial hearing. The subjective impression created for the blind traveler using the proposed aid will be that objects reflecting the ultrasonic beam will be heard as external sources of sound positioned in 3-dimensional space. In this way, the blind traveler will be able to more fully appreciate the spatial aspects of the external environment, enabling mobility with greater ease and confidence.